SRS Design for Unlicensed Carriers

ABSTRACT

There is disclosed a User Equipment for a MulteFire wireless communication network. The User Equipment comprises processing circuitry and a transmitter, the User Equipment being adapted for utilizing the processing circuitry and the transmitter for performing a Listen-Before-Talk (LBT) procedure for one or more transmission bandwidths; transmitting Physical Uplink Shared CHannel (PUSCH) signaling in a PUSCH subframe on one or more interlaces within the one or more transmission bandwidths; and transmitting Sounding Reference Signaling on the one or more interlaces in the PUSCH subframe.

TECHNICAL FIELD

The present disclosure pertains to wireless communication technology, inparticular to reference signals like Sounding Reference Signals, whichmay be used for unlicensed carriers.

BACKGROUND

The ongoing standalone LTE-U forum and future 3GPP Rel-14 work item onUplink Licensed-Assisted Access (LAA) intends to allow LTE UEs totransmit on the uplink in the unlicensed 5 GHz or license-shared 3.5 GHzradio spectrum. For the case of standalone LTE-U, respectively theMulteFire (MF) project, the initial random access and subsequent ULtransmissions take place entirely on the unlicensed spectrum. Regulatoryrequirements may not permit transmissions in the unlicensed spectrumwithout prior channel sensing. Since the unlicensed spectrum must beshared with other radios of similar or dissimilar wireless technologies,a so-called listen-before-talk (LBT) method needs to be applied forchannel sensing. LBT involves sensing the medium for a pre-definedminimum amount of time and backing off if the channel is busy.Therefore, the initial random access (RA) procedure for standalone LTE-Ushould involve as few transmissions as possible and also have lowlatency, such that the number of LBT operations can be minimized and theRA procedure can then be completed as quickly as possible.

Today, the unlicensed 5 GHz spectrum is mainly used by equipmentimplementing the IEEE 802.11 Wireless Local Area Network (WLAN)standard, also known under its marketing brand as “Wi-Fi.”

SUMMARY

It is an object of the present disclosure to provide improved approachesfor reference signaling in the context of carriers or frequency rangesaccessed utilizing an LBT based approach.

Accordingly, there is disclosed a terminal for a wireless communicationnetwork. The terminal is adapted for performing a Listen-Before-Talk(LBT) procedure for one or more transmission bandwidths. Moreover, theterminal is adapted for transmitting Physical Uplink Shared CHannel,PUSCH, signaling in a PUSCH subframe on one or more interlaces withinthe one or more transmission bandwidths. The terminal is further adaptedfor transmitting Sounding Reference Signaling (SRS) on the one or moreinterlaces in the PUSCH subframe. The terminal may comprisecorresponding processing and/or control circuitry, and/or radiocircuitry, e.g. a transmitter. Alternatively or additionally, theterminal may comprise one or more corresponding modules, e.g. a LBTmodule and/or a PUSCH module and/or a SRS module.

In particular, there may be considered a User Equipment (UE) for aMulteFire wireless communication network. The User Equipment comprisesprocessing circuitry and a transmitter. The User Equipment is adaptedfor utilizing the processing circuitry and the transmitter forperforming a Listen-Before-Talk, LBT, procedure for one or moretransmission bandwidths, as well as for transmitting Physical UplinkShared CHannel, PUSCH, signaling in a PUSCH subframe on one or moreinterlaces within the one or more transmission bandwidths, andtransmitting Sounding Reference Signaling on the one or more interlacesin the PUSCH subframe.

Moreover, a method of operating a terminal in a wireless communicationnetwork is described, the terminal being adapted for performing a LBTprocedure for one or more transmission bandwidths. The method comprisestransmitting Physical Uplink Shared CHannel, PUSCH, signaling in a PUSCHsubframe on one or more interlaces within the one or more transmissionbandwidths, and transmitting Sounding Reference Signaling on the one ormore interlaces in the PUSCH subframe.

Specifically, a method for operating a user Equipment in a MulteFirewireless communication network may be considered. The method comprisesperforming a Listen-Before-Talk, LBT, procedure for one or moretransmission bandwidths, transmitting Physical Uplink Shared CHannel,PUSCH, signaling in a PUSCH subframe on one or more interlaces withinthe one or more transmission bandwidths, as well as transmittingSounding Reference Signaling on the one or more interlaces in the PUSCHsubframe.

It may be considered that transmitting PUSCH signaling and/or referencesignaling, in particular SRS, is based on the LBT procedure. Inparticular, corresponding transmission may be performed (in relation toa transmission bandwidth) if the LBT procedure is successful. Generally,transmitting PUSCH signaling and/or reference signaling/SRS may be basedon a configuration. It may be considered that transmitting PUSCHsignaling and reference signaling/SRS is based on the same LBTprocedure. A LBT procedure may generally be performed before the relatedtransmitting, e.g. of PUSCH signaling and/or SRS. Generally, PUSCHsignaling and/or reference signaling may be considered uplink signaling.For different transmission bandwidth, different LBT procedure may beperformed, e.g. such that each LBT procedure is independent from theother procedures, e.g. in terms of possible results, and/or pertains toa different transmission bandwidth. Different transmission bandwidthsmay be neighboring transmission bandwidth and/or non-overlappingtransmission bandwidths).

Generally, transmitting Sounding Reference Signaling may comprisemultiplexing Sounding Reference Signaling transmitted on differentantenna ports via frequency division and/or based on cyclic shifts. Theantenna ports may be considered to be associated to the transmittingterminal.

It may be considered that transmitting Sounding Reference Signalingcomprises transmitting Sounding Reference Signaling at the end (in timedomain) of the PUSCH subframe, in particular in the last symbol of thePUSCH subframe. The last symbol may be a SC-FDMA (Single CarrierFrequency Division Multiple Access) symbol, or in some cases an OFDMA(Orthogonal Frequency Division Multiple Access) symbol, e.g. in thecontext of 5G technology, like 3GPP New Radio (NR). The SoundingReference Signaling may cover (only) the last or the two last symbols.Alternatively or additionally, the Sounding Reference Signaling maycover, in frequency domain, the same frequencies and/or subcarriers asthe PUSCH signaling, and/or a part thereof, e.g. as defined according tothe one or more interlaces.

There is also considered a network node for a wireless communicationnetwork. The network node is adapted for estimating channel conditionsbased on Sounding Reference Signaling received from at least oneterminal. Receiving Sounding Reference Signaling comprises receivingPhysical Uplink Shared CHannel, PUSCH, signaling in a PUSCH subframe onone or more interlaces, and receiving Sounding Reference Signaling onthe one or more interlaces in the PUSCH subframe. The network node maycomprise corresponding processing or control circuitry, and/orcorresponding radio circuitry, e.g. a receiver. Alternatively oradditionally, the network node may comprise one or more correspondingmodules, e.g. an estimating module and/or a receiving module and/or anSRS receiving module and/or a PUSCH receiving module.

Specifically, there is described an Access Point for a MulteFirewireless communication network, the Access Point comprising processingcircuitry and a receiver. The Access Point is adapted for utilizing theprocessing circuitry and the receiver for estimating channel conditionsbased on Sounding Reference Signaling received from at least one UserEquipment for the MulteFire wireless communication network; whereinreceiving Sounding Reference Signaling comprises receiving PhysicalUplink Shared CHannel, PUSCH, signaling in a PUSCH subframe on one ormore interlaces, and receiving Sounding Reference Signaling on the oneor more interlaces in the PUSCH subframe.

A method for operating a network node in a wireless communicationnetwork is discussed. The method comprises estimating channel conditionsbased on Sounding Reference Signaling received from at least oneterminal, wherein receiving Sounding Reference Signaling comprisesreceiving Physical Uplink Shared CHannel, PUSCH, signaling in a PUSCHsubframe on one or more interlaces, and receiving Sounding ReferenceSignaling on the one or more interlaces in the PUSCH subframe.

Moreover, a method for operating an Access Point in a MulteFire wirelesscommunication network is proposed. The method comprises estimatingchannel conditions based on Sounding Reference Signaling received fromat least one User Equipment for the MulteFire wireless communicationnetwork. Receiving Sounding Reference Signaling comprises receivingPhysical Uplink Shared CHannel, PUSCH, signaling in a PUSCH subframe onone or more interlaces, and receiving Sounding Reference Signaling onthe one or more interlaces in the PUSCH subframe.

Receiving of the PUSCH signaling and/or the SRS may be based on aconfiguration, which may be provided and/or configured by the networknode to the transmitting terminal/s. In particular, the receiver and/ornetwork node (respectively, it circuitry) may be configured to receiveand/or demodulate and/or decode and/or interpret received signalingaccording to the described transmitted structure of the signaling.

It may be considered that Sounding Reference Signaling is transmitted atthe end (in time domain) of the PUSCH subframe, in particular in thelast symbol of the PUSCH subframe. The last symbol may be a SC-FDMA(Single Carrier Frequency Division Multiple Access) symbol, or in somecases an OFDMA (Orthogonal Frequency Division Multiple Access) symbol,e.g. in the context of 5G technology, like 3GPP New Radio (NR). TheSounding Reference Signaling may cover (only) the last or the two lastsymbols. Alternatively or additionally, the Sounding Reference Signalingmay cover, in frequency domain, the same frequencies and/or subcarriersas the PUSCH signaling, and/or a part thereof, e.g. as defined accordingto the one or more interlaces.

In general, Sounding Reference Signaling transmitted on differentantenna ports and/or by different terminals may be multiplexed viafrequency division and/or based on cyclic shifts. Such multiplexing maybe based on configuration/s, e.g. determined by, and/or configured by,the network node. It may be considered that a network node configuring aterminal with a configuration knows the corresponding configuration. Itshould be noted that a transmission bandwidth for a receiver is thebandwidth it receives on (but denotes the bandwidth the transmittertransmitted on). Also, for a receiver signaling from differenttransmitters may be multiplexed, e.g. such that the receiver maydetermine which signaling stems from which transmitter. A configurationdetermined and/or provided by the network node or receiver may indicatedsuch multiplexing, for example for each individual terminal and/or for agroup of more than one terminal.

There may also be considered a program product comprising codeexecutable by control circuitry (or processing circuitry), the codecausing the processing or control circuitry to carry out and/or controlany one of the methods as described herein.

A carrier medium carrying and/or storing a program product as describedherein is disclosed as well.

The approaches described herein allow transmission of referencesignaling in the context (e.g., on the same frequency resources, e.g.subcarriers) as PUSCH signaling, without requiring an additional LBTprocedure to be performed. This increases reliability and allowsimproved use of resources subject to LBT access.

It may be considered that a terminal is implemented as a User Equipment,in particular a User Equipment for MulteFire. The network node may beimplemented a base station for MulteFire, which may be referred to asAccess Point.

A transmission bandwidth may represent a frequency bandwidth and/orrange. A transmission bandwidth may for example be a system bandwidth,and/or a bandwidth of carrier and/or a carrier aggregation, and/or abandwidth for which a LBT procedure has to be performed for access, e.g.according to regulation. An interlace may generally represent abandwidth within a transmission bandwidth and/or may be considered to beencompassed inside the bandwidth, and/or to represent a part of thebandwidth. An interlace may comprise a frequency range (e.g., acontinuous range, and/or two or more discontinuous ranges) fortransmission (e.g., scheduled and/or intended and/or reserved), inparticular for one terminal, e.g. for transmission on PUSCH and/or forreference signaling like SRS. In some variants, an interlace mayadditionally comprise a frequency range (e.g., a continuous range,and/or two or more discontinuous ranges) blocked and/or free from (bythe same UE or terminal) transmission (e.g., scheduled and/or intendedand/or reserved). This does not exclude that other terminals or devicesmay utilize blocked and/or free frequency ranges. In general, aninterlace may be block-based.

Sounding Reference Signaling may be reference signaling not related tothe PUSCH signaling, e.g. not intended and/or used for demodulatingand/or decoding such, and/or modulated and/or encoded independently ofPUSCH signaling.

It may generally be considered that, alternatively or additionally totransmitting PUSCH signaling, sPUCCH (shortened PUCCH) signaling istransmitted, e.g. in one or more interlaces, and/or in a similar manneras described in relation to PUSCH signaling. For sPUCCH, the SoundingReference Signaling may cover in time domain one, two, three or foursymbols, and/or, in frequency domain, the subcarriers used fortransmission of sPUCCH, and/or a part thereof. In some cases, the SRSsignaling may replace and/or represent the sPUCCH signaling. The sPUCCHSRS structure may depend on the presence of an LBT gap between sPUCCHand PUSCH, e.g. on whether a LBT procedure has to be performed betweenthe transmissions of sPUCCH signaling and PUSCH signaling.

A PUSCH subframe may be considered a subframe for which PUSCH signalingis scheduled and/or configured and/or intended. A network node may beadapted for configuring such subframe, and/or may configure suchsubframe, e.g. with UL grant signaling and/or with implicit scheduling.

Estimating a channel or channel conditions may comprise determining atiming and/or pathloss and/or interference associated to the channeland/or the signaling used for estimating.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are provided to illustrate concepts and approachesdescribed herein, and are not intended to limit their scope unlessspecifically stated otherwise.

The drawings comprise:

FIG. 1, showing a LTE downlink physical resource;

FIG. 2, showing the LTE time-domain structure;

FIG. 3, showing a Rel-12 uplink subframe;

FIG. 4, showing exemplary Licensed-assisted access (LAA) to unlicensedspectrum;

FIG. 5, showing an allocation of one first interlace;

FIG. 6, showing an example of SRS design;

FIG. 7, showing an example of SRS design;

FIG. 8, showing an example of SRS design;

FIG. 9, showing exemplary SRS in sPUCCH;

FIG. 10, schematically showing a terminal; and

FIG. 11, schematically showing a network node.

DETAILED DESCRIPTION

Long Term Evolution (LTE) is discussed in the following. It should benoted that in the context of this description, LTE may be seen asrepresentative for a wireless communication network using LBT to accessa carrier or spectrum and/or using reference signaling like SRS, butthat the approaches described herein are not necessarily limited to LTE,but rather could be used for other technologies, e.g. Narrowband and/orMulteFire.

LTE describes a telecommunication standard which uses OFDM in thedownlink and DFT-spread OFDM (also referred to as single-carrier FDMA,SC-FDMA) in the uplink. The basic LTE downlink physical resource canthus be seen as a time-frequency grid as illustrated in FIG. 1, whereeach resource element corresponds to one OFDM subcarrier during one OFDMsymbol interval. The uplink subframe has the same subcarrier spacing asthe downlink and the same number of SC-FDMA symbols in the time domainas OFDM symbols in the downlink.

FIG. 1 shows a LTE downlink physical resource.

In the time domain, LTE downlink transmissions are organized into radioframes of 10 ms, each radio frame consisting of ten equally-sizedsubframes of length Tsubframe=1 ms as shown in Figure. Each subframecomprises two slots of duration 0.5 ms each, and the slot numberingwithin a frame ranges from 0 to 19. For normal cyclic prefix, onesubframe consists of 14 OFDM symbols. The duration of each symbol isapproximately 71.4 μs (including cyclic prefix).

FIG. 2 shows the LTE time-domain structure.

Furthermore, the resource allocation in LTE is typically described interms of resource blocks (RB), where a RB corresponds to 12 contiguoussubcarriers in the frequency domain. Resource blocks are numbered in thefrequency domain, starting with 0 from one end of the system bandwidth.

In LTE, uplink transmissions are dynamically scheduled, i.e., in adownlink subframe the base station transmits control information aboutwhich terminals should transmit data to the eNB in subsequent subframes,and upon which resource blocks the data is transmitted. The uplinkresource grid is comprised of data and uplink control information in thePUSCH, uplink control information in the PUCCH, and various referencesignals such as demodulation reference signals (DMRS) and soundingreference signals (SRS). An example uplink subframe is shown in FIG. 3.

It is noted that UL DMRS and SRS are time-multiplexed into the ULsubframe, and SRS are always transmitted in the last symbol of a normalUL subframe. DMRS are used for coherent demodulation of PUSCH and PUCCHdata. The PUSCH DMRS is transmitted once every slot for subframes withnormal cyclic prefix, and is located in the fourth and eleventh SC-FDMAsymbols. SRS is not directly associated with other data or controlinformation, but may generally be used (by the receiving network node,e.g. eNodeB) to estimate the uplink channel quality for purposes offrequency-selective scheduling. In order to serve this purpose, it isnecessary that SRS from different UEs with different sounding bandwidthscan overlap. As illustrated in FIG. 3, interleaved FDMA is used for SRSwith a repetition factor of 2, which implies that in the configured SRSbandwidth, the SRS will be mapped to every other subcarrier in acomb-like fashion.

FIG. 3 shows a Rel-12 uplink subframe

Licensed-assisted access (LAA) to unlicensed spectrum using, in thisexample but not limited to, LTE is discussed in the following.

Up to now, the spectrum used by LTE is dedicated to LTE. This has theadvantage that LTE system does not need to care about the coexistenceissue and the spectrum efficiency can be maximized. However, thespectrum allocated to LTE is limited which cannot meet the everincreasing demand for larger throughput from applications/services.Therefore, a new study item has been initiated in 3GPP on extending LTEto exploit unlicensed spectrum in addition to licensed spectrum.Unlicensed spectrum can, by definition, be simultaneously used bymultiple different technologies. Therefore, LTE needs to consider thecoexistence issue with other systems such as IEEE 802.11 (Wi-Fi).Operating LTE in the same manner in unlicensed spectrum as in licensedspectrum can seriously degrade the performance of Wi-Fi as Wi-Fi willnot transmit once it detects the channel is occupied.

Furthermore, one way to utilize the unlicensed spectrum reliably is totransmit essential control signals and channels on a licensed carrier.That is, as shown in FIG. 4, a UE is connected to a PCell in thelicensed band and one or more SCells in the unlicensed band. In thisapplication a secondary cell in unlicensed spectrum is denoted aslicensed-assisted access secondary cell (LAA SCell).

FIG. 4 shows Licensed-assisted access (LAA) to unlicensed spectrum usingLTE carrier aggregation.

Standalone LTE in Unlicensed Spectrum is discussed in the following.

A new industry forum has been initiated on extending LTE to operateentirely on unlicensed spectrum in a standalone mode, which is referredto as “MulteFire” in marketing terms. There is no licensed carrier foressential control signals transmissions and control channels. Hence, allthe transmission needs to be carried on the unlicensed spectrum with noguaranteed channel access availability and also fulfill the regulatoryrequirements on the unlicensed spectrum.

The use of a carrier in an unlicensed spectrum should be done in a fairand equal manner for different devices. One component when securing thisfair sharing is to have requirements on how to distribute transmissionsover the system bandwidth. Here, requirements pertaining to at least twodifferent conditions/parameters are commonly found in regulations,namely pertaining to:

-   -   1. Occupied channel Bandwidth    -   2. Maximum Power Spectral Density (PSD)

For example, requirements to both these parameters are enforced for 5GHz carriers according to ETSI 301 893, while only maximum PSDrequirements are enforced in the US regulation for 5 GHz.

The Occupied bandwidth requirement is expressed in the form that thebandwidth containing 99% of the power of the signal shall be between 80%and 100% of the declared Nominal Channel Bandwidth. The currentunderstanding of this requirement is that it is tested (averaged) over atime interval longer than one sub-frame (1 ms). The frequencyallocations for one UE must thus vary between sub-frames in such a waythat the requirement is fulfilled. It is still an open issue if thisrequirement needs to be fulfilled for a UE which only transmits in asingle sub-frame, such as PRACH or with a single PUSCH.

Maximum PSD requirements exist in many different regions. For mostcases, the requirement is stated with a resolution bandwidth of 1 MHz.For example, the ETSI 301 893 specs requires 10 dBm/MHz for 5150-5350MHz. The implication of the PSD requirement on the physical layer designis that, without proper designs, a signal with small transmissionbandwidth will be limited in transmission power. This can negativelyaffect coverage of the operation. That is, the maximum PSD requirementis a binding condition that requires changes to UL transmissions inunlicensed spectrums.

There may be considered a LBT gap between sPUCCH and a subsequent PUSCHsubframe, where sPUCCH is between four to six symbols in length andfollows a partial DL subframe. If no gap is present, then what should besent during sPUCCH by users scheduled only for PUSCH/ePUCCH in the nextsubframe is a related open issue.

Generally, it should be noted that the terms “unlicensed” or “unlicensedcarrier” or “unlicensed spectrum” or “unlicensed bandwidth” may refer tocarrier/spectrum accessed using an LBT procedure, and the terms“LBT-accessed”, “LBT-accessed carrier” or “LBT-accessed spectrum”“LBT-accessed bandwidth” may be exchanged for these terms anywhere inthis disclosure unless specifically stated otherwise. LBT-accessed inthis context may refer to the bandwidth/carrier/frequency/spectrum onlybe accessible and/or only be accessed (e.g., according to regulationsand/or a standard) for transmission after a successful LBT procedure hasbeen performed, wherein a successful LBT procedure may allow access fortransmission (i.e., allow transmission) for a given amount of time,which e.g. may be defined by regulations or a standard. The amount oftime may in particular cover the duration of one or more subframes (1subframe for LTE has a duration of 1 ms).

Interlacing Design for UL transmission is discussed in the following.

Interlacing transmissions may be considered as a means to give LAA (orgenerally, UL signals on carriers/spectrum using LBT/channels sensing)UL signals with small BW higher transmission powers when needed (and, toa lesser extent, to satisfy the transmission BW requirement). Theinterlacing transmissions can be done on a PRB (Physical Resource Block)basis. Interlacing on a sub-carrier basis may produce transmissionssuffering from ICI (Inter Carrier Interference) in scenarios with largefrequency offsets or with a delay spread larger than the cyclic prefix.This design is also referred to as Block-Interleaved FDMA (B-IFDMA).

One interlace is illustrated in FIG. 5, in a design with 5 interlacesfor an example of 20 MHz system bandwidth with a maximum of 100 RBsavailable for transmission. As shown in the figure, a uniform spread ofthe RBs may be considered, i.e., uniform interlaces where each interlacecontains 100/5=20 RBs. The figure to the right shows the first 1.2 MHzof the same allocation. The darker lines represent example boundaries ofthe PSD requirement measurement intervals (1 MHz resolution bandwidth).The light stripes represent the allocated RBs for the interlace.

FIG. 5 shows an allocation of one first interlace, in a design with 5uniform interlaces for an example of 20 MHz bandwidth (i.e., 100/5=20 RBper interlace). The figure to the right shows the first 1.2 MHz of thesame allocation. The darker lines represent the boundaries of the PSDrequirement measurement intervals (1 MHz resolution bandwidth). Thelight stripes represent the allocated RBs for the interlace.

In LAA/standalone LTE-U uplink, the SRS originally designed for LTE onlicensed spectrum cannot be reused.

-   -   1. On unlicensed carriers, channel access (for transmission)        operates based on the LBT mechanism. Channel access availability        for SRSs to be transmitted on unlicensed carriers is not        guaranteed.    -   2. In licensed LTE, the SRSs are partly used for channel        sounding to allow for frequency-selective scheduling in the UL.        For this purpose, the SRS is designed to span across the full        bandwidth. In the unlicensed band with interlaced UL resource        allocation, not much gain can be provided by frequency-selective        scheduling because the PUSCH transmission from different UEs may        be evenly distributed across the spectrum. So, the SRS design        for unlicensed carries mainly serves to fulfill demands such as        UL MIMO sounding and uplink timing estimation.

The present disclosure physical-layer design of SRS for LBT-accesseduplink transmissions, in particular for a LAA/stand-alone LTE-U uplink,including several design options and examples. In the proposed design,the SRSs may be transmitted together with PUSCH signaling, e.g. in orderto avoid extra LBT. The SRS may occupy the last (SC-FDMA) symbol in anUL subframe, for example with PUSCH interlaced on RB basis spanning thefull transmission bandwidth. In each interlace, the SRSs may betransmitted from different users/antenna ports multiplexed via frequencydivision and/or cyclic shifts.

The approaches described herein provide at least one of:

-   -   1. SRS transmission on unlicensed carriers is enabled without        extra LBT.    -   2. Similar functionalities can be maintained as the SRSs in        licensed LTE.    -   3. Both aspects of SRS measurements and multiple subframe grants        can benefit from placing SRS in the last symbol of a subframe.

The approaches are illustrated in more detail by a number of exemplaryembodiments. It should be noted that proposed methods can be applied todifferent variations of wireless communication systems, e.g. LTE,operating in unlicensed spectrum, such as LAA and standalone LTE-U UL.

The following design options describe different examples of referencesignal patterns in the context of LTE and using SRS. However, suchpattern may be used for other (UL/SL) reference signaling onLBT-accessed bandwidths, e.g. in MulteFire systems, in which theeNodeB's functionality could be provided by an Access Point.

An exemplary SRS design option 1 is described in the following.

In order to avoid extra LBT, the SRS is only transmitted together withPUSCH in the same subframe, where the PUSCH may span the whole bandwidth(e.g., a carrier, and/or a bandwidth allowed and/or prescribed byregulations or a standard) by interlacing.

As illustrated in FIG. 6, within one interlace, e.g. interlace #0, theSRS occupies the last (SC-FDMA) symbol. In frequency domain, the SRSspans the whole bandwidth, e.g. by interlacing. Multiplexing the SRSstransmitted from multiple antenna ports per UE and/or multiples userscan be based, in particular be solely based, on cyclic shifts.

FIG. 6 shows an example of SRS design option 1.

An exemplary SRS design option 2 is described in the following.

In another option, within each subframe of one interlace, in addition tocyclic shifts, SRSs can be multiplexed in frequency domain i.e. in acomb-like fashion (transmitted on every other subcarrier). An example isillustrated in FIG. 7, where SRS on even antenna ports are transmittedon even subcarriers while SRS for odd antenna ports are transmitted onodd subcarriers (2-comb), or in the opposite way.

FIG. 7 shows an example of SRS design option 2

An exemplary SRS design option 3 is described in the following.

In this option, which may be in addition to and/or based on option 2,multiplexing by frequency division and cyclic shifts in each subframe ofone interlace is highly flexible and configurable. For example, the combuse, i.e. the subcarrier mapping per user or antenna port can beconfigurable. The configuration information can be indicated by theeNodeB or Access Point in the UL grant and/or higher layer signaling. Inanother example, the comb use factor may not be limited to 2 (occupyingevery other subcarrier). A higher comb use factor, for example, 4-combmay be used for multiplexing more users.

Generally, multiplexing multiple users and/or antenna ports can becarried out by various combinations of frequency division and cyclicshifts. For example, to multiplex 4 antenna ports within one interlace,4 combs without cyclic shifts and 2 combs with two different cyclicshifts for antenna 1/3 and 2/4 respectively are two typical options.

An exemplary SRS design option 4 is described in the following.

In this option, SRS transmission per user/terminal involves twointerlaces and 2-comb is used in each interlace. As exemplified in FIG.8, SRS is transmitted on the even subcarriers in the assigned interlacex (interlace #0 in the figure) and on the odd subcarriers in theinterlace mod(x+5, 10) (interlace #5 in the figure).

Another example, alternatively, is that SRS is transmitted on the evensubcarriers of interlaces x and mod(x+5, 10) if x<5 while on the oddsubcarriers if x>=5.

Note that, if a UE is assigned half of the interlaces, its SRS willcover every PRB in the system BW. When two UEs are assigned half of theinterlaces each, their SRS signals are multiplexed across all thesubcarriers in the channel BW.

The above design option can be extended to a more general one. SRStransmission per user/terminal may involve m(>=2) interlaces and an(>=2)-comb is used in each interlace. In one example, the multiplexingoccurs in frequency domain only, i.e. SRS per user/antenna port istransmitted on a specific set of interlaces and on a specific comb ineach such interlace. The configuration for such SRS transmission isflexible. In another example, in addition to the last example, cyclicshifts can be used to further enhance the multiplexing capacity.

FIG. 8 shows an example of SRS design option 4.

An exemplary SRS design option 5 is described in the following.

This option addresses what should be sent by users that do not haveACK/NACK or CSI transmission in the MulteFire sPUCCH, and are scheduledfor PUSCH or ePUCCH transmission immediately after sPUCCH. As anexample, users sending feedback in sPUCCH and users scheduled in ULsubframes after the sPUCCH may both perform UL LBT prior to the start ofthe sPUCCH, and no additional LBT gap is present between sPUCCH and thenext UL subframe. In this case, SRS is used as an initial signal by theusers/terminals that do not transmit feedback during sPUCCH. This SRScan be used at the eNB for timing and frequency estimation, in additionto MIMO sounding.

FIG. 9 shows SRS in sPUCCH.

A non-limiting example is shown in FIG. 9, where a SRS signal isrepeated across the sPUCCH region in time on a pre-specified interlace,with the same cyclic shift in all four symbols. All users that do notsend feedback in the sPUCCH may be assigned the same interlace for theirSRS-based initial signal. In another case, different cyclic shifts orcombs may be configured in each symbol for a particular user. In otherexamples, the frequency domain allocation of the SRS may be based on oneor more of the previously described SRS design options.

FIG. 10 schematically shows a terminal 10, which may be implemented inthis example as a User Equipment. Terminal 10 comprises controlcircuitry 20, which may comprise a controller connected to a memory. Areceiving module and/or transmitting module and/or control or processingmodule and/or CIS receiving module and/or scheduling module, may beimplemented in and/or executable by, the control circuitry 20, inparticular as module in the controller. Terminal 10 also comprises radiocircuitry 22 providing receiving and transmitting or transceivingfunctionality, the radio circuitry 22 connected or connectable to thecontrol circuitry. An antenna circuitry 24 of the terminal 10 isconnected or connectable to the radio circuitry 22 to collect or sendand/or amplify signals. Radio circuitry 22 and the control circuitry 20controlling it are configured for cellular communication with a networkon a first cell/carrier and a second cell/carrier, in particularutilizing E-UTRAN/LTE resources as described herein. The terminal 10 maybe adapted to carry out any of the methods for operating a terminaldisclosed herein; in particular, it may comprise correspondingcircuitry, e.g. control circuitry.

FIG. 11 schematically show a network node or base station 100, which inparticular may be an eNodeB or an MulteFire Access Point. Network node100 comprises control circuitry 120, which may comprise a controllerconnected to a memory. A receiving module and/or transmitting moduleand/or control or processing module and/or scheduling module and/or CISreceiving module, may be implemented in and/or executable by the controlcircuitry 120. The control circuitry is connected to control radiocircuitry 122 of the network node 100, which provides receiver andtransmitter and/or transceiver functionality. An antenna circuitry 124may be connected or connectable to radio circuitry 122 for signalreception or transmittance and/or amplification. The network node 100may be adapted to carry out any of the methods for operating a networknode disclosed herein; in particular, it may comprise correspondingcircuitry, e.g. control circuitry.

This disclosure describes several options of SRS design for SRStransmission on unlicensed carriers. The SRS may occupy the lastmulticarrier symbol (i.e., last OFDM/B-IFDMA symbol), e.g. in each ULsubframe or subcarrier of the interlace(s). The proposed design optionsdescribe the various mechanisms through which SRSs transmitted fromdifferent users/antenna ports can be multiplexed.

Generally, there may be considered a terminal for a wirelesscommunication network. The terminal may be adapted for, and/or comprisean LBT module for, performing a LBT-procedure and/or LBT access for oneor more (transmission) bandwidths. The terminal may be adapted and/orconfigured for, and/or comprise a transmit module for transmittingreference signaling via the bandwidth, in particular based on a(successful) LBT procedure and/or LBT access performed pertaining to thebandwidth. Transmitting may be based on a configuration. The terminalmay be adapted to be configured, and/or comprise a configuration modulefor being configured accordingly.

There may be considered a method for operating a terminal for and/or ina wireless communication network. The method may comprise performing aLBT-procedure and/or LBT access for one or more (transmission)bandwidths. Generally, the method may comprise transmitting referencesignaling via the (transmission bandwidth), in particular based on a(successful) LBT procedure and/or LBT access performed pertaining to thebandwidth. Transmitting may be based on a configuration. The method maycomprise receiving a corresponding configuration, e.g. from a networknode.

There may be considered a network node for a wireless communicationnetwork. The network node may be adapted for, and/or comprise aconfiguring module for, configuring a terminal with a configuration fortransmitting reference signaling, in particular the configuration maypertain to reference signaling on a (transmission) bandwidth accessedand/or accessible (for the terminal) based on a (successful) LBTprocedure or access performed by the terminal. The network node may beadapted for, and/or comprise a receiving module for, receiving referencesignaling based on the configuration. Alternatively or additionally, thenetwork node may be adapted for, and/or comprise an estimating modulefor, estimating channel conditions based on the received referencesignaling.

Moreover, there may be considered a method for operating a network nodefor and/or in a wireless communication network. The method may compriseconfiguring a terminal with a configuration for transmitting referencesignaling, in particular the configuration may pertain to referencesignaling on a (transmission) bandwidth accessed and/or accessible (forthe terminal) based on a (successful) LBT procedure or access performedby the terminal. The method may comprise receiving reference signalingbased on the configuration. Alternatively or additionally, the methodmay comprise estimating channel conditions based on the receivedreference signaling.

Reference signaling may generally comprise one or more referencesignals, in particular SRS. A reference signal may generally beconsidered to cover and/or occur in and/or be defined pertaining to(only) one resource element. A plurality of reference signals may coverand/occur in more than one resource elements, which may be arranged in a(reference signal) pattern in one or more interlaces and/or atransmission bandwidth.

Transmitting reference signaling may be part of and/or compriseinterlacing the bandwidth and/or using one or more interlaces coveringand/or included in the bandwidth. Alternatively or additionally,transmitting reference signaling may be performed based on a (referencesignal) pattern. Transmitting reference signaling may be on a sidelinkand/or uplink.

A pattern, in particular a reference signal pattern and/or an interlacepattern, may be configurable and/or be based on a configuration. Theconfiguration may be configured by a network node like an eNodeB, whichmay in particular the node which is the intended receiver of thereference signaling. A reference signal pattern may in particular be acomb pattern, and/or one of the patterns described herein in particularregarding designs 1 to 5.

For different interlaces there may be different reference signalingpatterns, e.g. based on corresponding configuration.

The reference signals of a pattern may generally be associated to thelast symbol of a time structure like a subframe used for (UL)transmission, e.g., if a reference signal is transmitted or to betransmitted in a subcarrier/resource element. A signal being associatedto a time unit, e.g. a symbol, may refer to the signal being transmittedat the time or time interval associated to and/or being defined for thetime unit or symbol.

A comb may be considered to be pattern may defining an arrangement (inparticular regarding frequency) in which between (each) twosubcarriers/resource elements on which a reference signal istransmitted/to be transmitted there is at least one subcarrier/resourceelement (in frequency domain) which is used for transmission of othersignaling, e.g. for channel transmission, in particular transmission onPUCCH (Physical Uplink Control CHannel), sPUCCH (shortened PUCCH, forshortened Transmission Time Intervals), ePUCCH (enhanced PUCCH), PUSCH,etc. Alternatively, a comb may define an arrangement in which betweeneach two subcarriers/resource elements on which a reference signalassociated to a (first) antenna element or antenna port or antennasubarray or virtual antenna is transmitted/to be transmitted there is atleast one subcarrier/resource element (in frequency domain) which isused for transmitting reference signaling associated to at least oneother (second) antenna element or antenna port or antenna subarray orvirtual antenna transmission.

Generally, a comb may define a pattern in which between two neighboring(having the closest distance to each other in terms of frequency)subcarriers/REs used for reference signaling there are arranged one ormore other subcarriers/REs used for other signaling, wherein othersignaling may comprise signaling on specific channels and/or referencesignaling utilizing a different/other antenna sub-arrangement.

For a n-comb, there may be n-1 other subcarriers/resource elementsbetween two subcarriers and/or resource elements used for transmittingand/or allocated for reference signaling (associated to a (first)antenna element/port/subarray or virtual antenna). Othersubcarriers/resource elements may refer to subcarriers/resource elementsassociated to different kinds of signaling and/or a different antennasub-arrangement and/or different antenna port. An antennasub-arrangement may refer to a sub-division of an antenna arrangement orantenna array, wherein a sub-arrangement may comprise a (physical)antenna element, a subarray 8 which may have one or more physicalantenna elements) and/or virtual antenna (which may be associated to oneor more physical antenna elements), and/or may pertain to an associatedantenna port. An antenna port may generally be an interface forproviding a signal to an antenna sub-arrangement for transmission usingthe (physical) antenna elements of the antenna sub-arrangement. It maybe considered that an antenna port provides a mapping of signaling, inparticular reference signaling, to the antenna element/s.

A pattern may be scheduled, e.g. according to a configuration.Scheduling and/or allocating a pattern may comprise and/or correspond toconfiguring the terminal with the pattern. A pattern may generally referto resources used for uplink and/or sidelink transmissions. Differentpatterns may be configured for different interlaces of a transmissionbandwidth. A bandwidth may comprise and/or be covered by a plurality ofinterlaces.

Performing an LBT procedure and/or LBT access pertaining to a bandwidthmay refer to performing the LBT procedure or access to access thebandwidth for transmission.

Reference signaling may comprise one or more reference signals, inparticular SRS.

A configuration may generally indicate and/or prescribed a pattern, e.g.a reference signal pattern and/or an interlace pattern, and/or scheduleand/or allocate (uplink and/or sidelink) resources accordingly. It isnoted that, when using LBT-procedures, allocating a resource fortransmission and/or corresponding configuration alone does not allow ornecessitate that the resource may be used for transmission.

There may be considered a network node adapted for performing any one ofthe methods for operating a network node described herein.

There may be considered a terminal adapted for performing any one of themethods for operating a terminal described herein.

A wireless transmitter may be a terminal or a network node.

There is also disclosed a program product comprising code executable bycontrol circuitry, the code causing the control circuitry to carry outand/or control any one of the method for operating a terminal or networknode as described herein, in particular if executed on controlcircuitry, which may be control circuitry of a terminal or a networknode as described herein.

Moreover, there is disclosed a carrier medium carrying and/or storing atleast any one of the program products described herein and/or codeexecutable by control circuitry, the code causing the control circuitryto perform and/or control at least any one of the methods describedherein. Generally, a carrier medium may be accessible and/or readableand/or receivable by control circuitry. Storing data and/or a programproduct and/or code may be seen as part of carrying data and/or aprogram product and/or code. A carrier medium generally may comprise aguiding/transporting medium and/or a storage medium. Aguiding/transporting medium may be adapted to carry and/or carry and/orstore signals, in particular electromagnetic signals and/or electricalsignals and/or magnetic signals and/or optical signals. A carriermedium, in particular a guiding/transporting medium, may be adapted toguide such signals to carry them. A carrier medium, in particular aguiding/transporting medium, may comprise the electromagnetic field,e.g. radio waves or microwaves, and/or optically transmissive material,e.g. glass fiber, and/or cable. A storage medium may comprise at leastone of a memory, which may be volatile or non-volatile, a buffer, acache, an optical disc, magnetic memory, flash memory, etc.

A (transmission) bandwidth may refer to a frequency range or band orspectrum, which may be accessible for transmission based on LBT, inparticular based on a successful LBT-process. The bandwidth may cover acontinuous range of frequencies, from a lower border frequency to anupper border frequency. The width (in frequency) of, and/or the (rangeof) frequencies covered by, the bandwidth or band or spectrum may bedefined and/or be based on regulations and/or standards. The bandwidthin particular may cover a plurality of subcarriers and/or resourceblocks (respectively carriers) in frequency. It may be considered thatthe bandwidth is assigned to a time/frequency structure, which may beaccording to a standard like LTE. The bandwidth may be assigned to atime structure like that of a subframe structure and/or be divided forexample into subcarriers and/or frequency units associated with resourceblocks and/or resource elements. The (maximum) duration for transmissionand/or the bandwidth available for transmission after a successfulLBT-access may be defined by regulation and/or a standard. The actualduration of transmission may be dependent on the amount of data to betransmitted. Between two transmission events, there may be required theperformance of a successful LBT-process and/or a backoff-period ornon-transmission gap.

A bandwidth may be interlaced, such that only parts of the bandwidth areused for transmission (if allowed according to LBT). A part of thebandwidth used for transmission may be assigned to a specific channel,in particular a physical channel like e.g. the PUSCH or PUCCH. Differentparts of the bandwidth (and/or different bandwidths) may be assigned todifferent (physical) channels. The channels may be according to astandard definition, in particular according to LTE. A bandwidth may becovered by a (bandwidth) pattern. The pattern may described/prescribehow parts of a bandwidth (e.g. subcarriers) used for transmission areused, e.g. which parts of the bandwidth used for transmission areassigned to specific signals (e.g., reference signals like SRS) and/orfor other signaling, e.g. according to a channel. The pattern may bebased on a configuration, which may be configured by a network, inparticular a network node like an eNodeB. A pattern pertaining toreference signals (SRS), and/or describing the location of referencesignals (SRS) in a bandwidth may be referred to as reference signalpattern. Different parts of a bandwidth may be allocated to differentantenna elements/antenna ports/antennas (e.g., virtual antennas) fortransmission, e.g. in a MIMO system. Accordingly, resources in abandwidth may be associated to different antenna elements and/or todifferent antenna subarrays. A (reference signal) pattern may besuperimposed on an interlace pattern.

A terminal and/or network node may comprise and/or be connected orconnectable (e.g., for transmission) to an antenna array, which maycomprise one or more (physical) antenna elements. (Physical) antennaelements may be arranged (and/or be configured or configurable) indifferent subarrays and/or virtual antenna elements.

In the context of this description, wireless communication may becommunication, in particular transmission and/or reception of data, viaelectromagnetic waves and/or an air interface, in particular radiowaves, e.g. in a wireless communication network and/or utilizing a radioaccess technology (RAT). The communication may involve one or more thanone terminal connected to a wireless communication network and/or morethan one node of a wireless communication network and/or in a wirelesscommunication network. It may be envisioned that a node in or forcommunication, and/or in, of or for a wireless communication network isadapted for communication utilizing one or more RATs, in particularLTE/E-UTRA. A communication may generally involve transmitting and/orreceiving messages, in particular in the form of packet data. A messageor packet may comprise control and/or configuration data and/or payloaddata and/or represent and/or comprise a batch of physical layertransmissions. Control and/or configuration data may refer to datapertaining to the process of communication and/or nodes and/or terminalsof the communication. It may, e.g., include address data referring to anode or terminal of the communication and/or data pertaining to thetransmission mode and/or spectral configuration and/or frequency and/orcoding and/or timing and/or bandwidth as data pertaining to the processof communication or transmission, e.g. in a header.

Each node or terminal involved in communication may comprise radiocircuitry and/or control circuitry and/or antenna circuitry, which maybe arranged to utilize and/or implement one or more than one radioaccess technologies. Radio circuitry of a node or terminal may generallybe adapted for the transmission and/or reception of radio waves, and inparticular may comprise a corresponding transmitter and/or receiverand/or transceiver, which may be connected or connectable to antennacircuitry and/or control circuitry. Control circuitry, which maygenerally be referred to as processing circuitry, of a node or terminalmay comprise a controller and/or memory arranged to be accessible forthe controller for read and/or write access. The controller may bearranged to control the communication and/or the radio circuitry and/orprovide additional services. Circuitry of a node or terminal, inparticular control circuitry or processing circuitry, e.g. a controller,may be programmed to provide the functionality described herein. Acorresponding program code may be stored in an associated memory and/orstorage medium and/or be hardwired and/or provided as firmware and/orsoftware and/or in hardware. A controller may generally comprise aprocessor and/or microprocessor and/or microcontroller and/or FPGA(Field-Programmable Gate Array) device and/or ASIC (Application SpecificIntegrated Circuit) device. More specifically, it may be considered thatcontrol circuitry comprises and/or may be connected or connectable tomemory, which may be adapted to be accessible for reading and/or writingby the controller and/or control circuitry. Radio access technology maygenerally comprise, e.g., Bluetooth and/or Wi-Fi and/or WIMAX and/orcdma2000 and/or GERAN and/or UTRAN and/or in particular E-Utran and/orLTE and/or NR. A communication may in particular comprise a physicallayer (PHY) transmission and/or reception, onto which logical channelsand/or logical transmission and/or receptions may be imprinted orlayered.

A wireless transmitter may be (or be comprised in) a node of a wirelesscommunication network and/or may be implemented as a terminal and/orUser Equipment and/or network node and/or base station and/or relay nodeand/or any device generally adapted for communication in a wirelesscommunication network, in particular cellular communication.

A cellular network may comprise a network node, in particular a radionetwork node, which may be connected or connectable to a core network,e.g. a core network with an evolved network core, e.g. according to LTEor NR. A network node may e.g. be a base station. The connection betweenthe network node and the core network/network core may be at leastpartly based on a cable/landline connection. Operation and/orcommunication and/or exchange of signals involving part of the corenetwork, in particular layers above a base station or eNB, and/or via apredefined cell structure provided by a base station or eNB, may beconsidered to be of cellular nature or be called cellular operation.Operation and/or communication and/or exchange of signals withoutinvolvement of layers above a base station and/or without utilizing apredefined cell structure provided by a base station or eNB, may beconsidered to be D2D communication or operation, in particular, if itutilizes the radio resources, in particular carriers and/or frequencies,and/or equipment (e.g. circuitry like radio circuitry and/or antennacircuitry, in particular transmitter and/or receiver and/or transceiver)provided and/or used for cellular operation. It may be considered that anetwork node is implemented as an access point, in particular aMulteFire Access Point (MF Access Point).

A terminal may be implemented as a User Equipment. A terminal or a UserEquipment (UE) may generally be a device configured for wirelessdevice-to-device communication and/or a terminal for a wireless and/orcellular network, in particular a mobile terminal, for example a mobilephone, smart phone, tablet, PDA, etc. A User Equipment or terminal maybe a node of or for a wireless communication network as describedherein, e.g. if it takes over some control and/or relay functionalityfor another terminal or node. It may be envisioned that terminal or aUser Equipment is adapted for one or more RATs, in particular LTE/E-UTRAor NR. A terminal or User Equipment may generally be proximity services(ProSe) enabled, which may mean it is D2D capable or enabled. It may beconsidered that a terminal or User Equipment comprises radio circuitryand/control circuitry for wireless communication. Radio circuitry maycomprise for example a receiver or receiver device and/or transmitter ortransmitter device and/or transceiver or transceiver device. Controlcircuitry may include a controller, which may comprise a microprocessorand/or microcontroller and/or FPGA (Field-Programmable Gate Array)device and/or ASIC (Application Specific Integrated Circuit) device. Itmay be considered that control circuitry comprises or may be connectedor connectable to memory, which may be adapted to be accessible forreading and/or writing by the controller and/or control circuitry. Itmay be considered that a terminal or User Equipment is configured to bea terminal or User Equipment adapted for LTE/E-UTRAN.

A network node or base station may be any kind of base station of awireless and/or cellular network adapted to serve one or more terminalsor User Equipments. It may be considered that a base station is a nodeor network node of a wireless communication network. A network node orbase station may be adapted to provide and/or define and/or to serve oneor more cells of the network and/or to allocate frequency and/or timeresources for communication to one or more nodes or terminals of anetwork. Generally, any node adapted to provide such functionality maybe considered a base station. It may be considered that a base stationor more generally a network node, in particular a radio network node,comprises radio circuitry and/or control circuitry for wirelesscommunication. It may be envisioned that a base station or network nodeis adapted for one or more RATs, in particular LTE/E-UTRA or NR. Radiocircuitry may comprise for example a receiver device and/or transmitterdevice and/or transceiver device. Control circuitry may include acontroller, which may comprise a microprocessor and/or microcontrollerand/or FPGA (Field-Programmable Gate Array) device and/or ASIC(Application Specific Integrated Circuit) device. It may be consideredthat control circuitry comprises or may be connected or connectable tomemory, which may be adapted to be accessible for reading and/or writingby the controller and/or control circuitry. A base station may bearranged to be a node of a wireless communication network, in particularconfigured for and/or to enable and/or to facilitate and/or toparticipate in cellular communication, e.g. as a device directlyinvolved or as an auxiliary and/or coordinating node. Generally, a basestation may be arranged to communicate with a core network and/or toprovide services and/or control to one or more User Equipments and/or torelay and/or transport communications and/or data between one or moreUser Equipments and a core network and/or another base station and/or beProximity Service enabled. An eNodeB (eNB) may be envisioned as anexample of a base station, e.g. according to an LTE standard. A basestation may generally be proximity service enabled and/or to providecorresponding services. It may be considered that a base station isconfigured as or connected or connectable to an Evolved Packet Core(EPC) and/or to provide and/or connect to corresponding functionality.The functionality and/or multiple different functions of a base stationmay be distributed over one or more different devices and/or physicallocations and/or nodes. A base station may be considered to be a node ofa wireless communication network. Generally, a base station may beconsidered to be configured to be a coordinating node and/or to allocateresources in particular for cellular communication between two nodes orterminals of a wireless communication network, in particular two UserEquipments.

It may be considered that for cellular communication there is providedat least one uplink (UL) connection and/or channel and/or carrier and atleast one downlink (DL) connection and/or channel and/or carrier, e.g.via and/or defining a cell, which may be provided by a network node, inparticular a base station or eNodeB. An uplink direction may refer to adata transfer direction from a terminal to a network node, e.g. basestation and/or relay station. A downlink direction may refer to a datatransfer direction from a network node, e.g. base station and/or relaynode, to a terminal. UL and DL may be associated to different frequencyresources, e.g. carriers and/or spectral bands. A cell may comprise atleast one uplink carrier and at least one downlink carrier, which mayhave different frequency bands. A network node, e.g. a base station oreNodeB, may be adapted to provide and/or define and/or control one ormore cells, e.g. a PCell and/or a LA cell.

A network node, in particular a base station, and/or a terminal, inparticular a UE, may be adapted for communication in spectral bands(frequency bands) licensed and/or defined for LTE. In addition, anetwork node, in particular a base station, and/or a terminal, inparticular a UE, may be adapted for communication in freely availableand/or unlicensed/LTE-unlicensed spectral bands (frequency bands), e.g.around 5 GHz.

An LBT carrier may refer to a carrier or cell on which an LBT procedureis to be performed before transmitting, in particular in an unlicensedspectrum or frequency band. The expression LBT carrier may be usedinterchangeably with LA SCell or unlicensed cell or unlicensed carrier.A carrier may be associated to a spectrum and/or frequency band and/or achannel. A cell may have associated to it at least one channel orcarrier; it may be considered that a cell comprises different carriersor channels for uplink or downlink. A cell may comprise one or more thanone frequency bands (e.g. subcarriers) and/or channels for each datatransmission direction (uplink and downlink). There may be differentnumber of channels or frequency bands for uplink and downlink.

A LBT procedure may generally refer to a procedure determining whether atransmission is possible or admissible (in particular, for the node orterminal performing the LBT) to transmit in a given spectrum orfrequency band or cell or carrier, in particular on a LA SCell or LBTcarrier, and/or whether another transmission is taking place, whichwould indicate that no own transmission is possible.

A LBT procedure may comprise listening to a channel and/or spectrumand/or frequency band and/or carrier, on which it may be performed whichmay be intended for a transmission), in particular listening fortransmission from another source and/or transmitter, which may comprisereceiving and/or detecting the energy or power of transmissions orradiation in this channel and/or spectrum and/or frequency band. Failureof a LBT procedure may indicate that transmissions on the channel orcell or frequency band have been detected, so that it may be consideredblocked by or for another transmitter, e.g. due to detection of apre-determined energy or power level. Failure of a LBT procedure may beconsidered to be equivalent to a determination of achannel/spectrum/band/carrier to be Busy.

A successful LBT procedure may indicate thechannel/spectrum/band/carrier to be Idle. Generally, a LBT procedure maybe performed before transmission and/or before a scheduled transmission.It may be considered that a LBT procedure is performed frame-and/orsubframe-based and/or in synchronization to the timing structure of acell, in particular a PCell. A LBT procedure may comprise one or moreCCA procedures.

Listening and/or performing a CCA may comprise determining and/ormeasuring the power and/or energy on the channel/spectrum/band/carrierlistened to (and/or on which CCA is performed) over predetermined time.The measured power or energy may be compared to a threshold to determineBusy or Idle states.

A storage medium may be adapted to store data and/or store instructionsexecutable by control circuitry and/or a computing device, theinstruction causing the control circuitry and/or computing device tocarry out and/or control any one of the methods described herein whenexecuted by the control circuitry and/or computing device. A storagemedium may generally be computer-readable, e.g. an optical disc and/ormagnetic memory and/or a volatile or non-volatile memory and/or flashmemory and/or RAM and/or ROM and/or EPROM and/or EEPROM and/or buffermemory and/or cache memory and/or a database.

Resources or communication resources or radio resources may generally befrequency and/or time resources (which may be called time/frequencyresources). Allocated or scheduled resources may comprise and/or referto frequency-related information, in particular regarding one or morecarriers and/or bandwidth and/or subcarriers and/or time-relatedinformation, in particular regarding frames and/or slots and/orsubframes, and/or regarding resource blocks and/or time/frequencyhopping information. Allocated resources may in particular refer to ULresources, e.g. UL resources for a first wireless device to transmit toand/or for a second wireless device. Transmitting on allocated resourcesand/or utilizing allocated resources may comprise transmitting data onthe resources allocated, e.g. on the frequency and/or subcarrier and/orcarrier and/or timeslots or subframes indicated. It may generally beconsidered that allocated resources may be released and/or de-allocated.A network or a node of a network, e.g. an allocation or network node,may be adapted to determine and/or transmit corresponding allocationdata indicating release or de-allocation of resources to one or morewireless devices, in particular to a first wireless device.

Allocation data may be considered to be data scheduling and/orindicating and/or granting resources allocated by the controlling orallocation node, in particular data identifying or indicating whichresources are reserved or allocated for communication for a wirelessdevice or terminal and/or which resources a wireless device or terminalmay use for communication and/or data indicating a resource grant orrelease, in particular pertaining to uplink and/or downlink resources. Agrant or resource or scheduling grant or scheduling data (which, inparticular, may pertain to information regarding and/or representingand/or indicating scheduling of resources) may be considered to be oneexample of allocation data. Allocation data may in particular compriseinformation and/or instruction regarding a configuration and/or forconfiguring a terminal, e.g. indicating a measurement configuration tobe used. It may be considered that an allocation node or network node isadapted to transmit allocation data directly to a node or wirelessdevice and/or indirectly, e.g. via a relay node and/or another node orbase station.

Allocation data may comprise control data and/or be part of or form amessage, in particular according to a pre-defined format, for example aDCI format, which may be defined in a standard, e.g. LTE. Allocationdata may comprise configuration data, which may comprise instruction toconfigure and/or set a User Equipment for a specific operation mode, inparticular a measurement mode, e.g. in regard to the use of receiverand/or transmitter and/or transceiver and/or use of transmission (e.g.TM) and/or reception mode, and/or may comprise scheduling data, e.g.granting resources and/or indicating resources to be used fortransmission and/or reception. A scheduling assignment may be consideredto represent scheduling data and/or be seen as an example of allocationdata. A scheduling assignment may in particular refer to and/or indicateresources to be used for communication or operation. Configuration orallocation data may comprise an indication for configuring a terminalfor interlacing, in particular resources available, for whichinterlacing may be performed, e.g. a set of interlaces and/or how tointerlace and/or a mapping for interlacing and/or a frequency range onwhich to perform interlacing, wherein the frequency range may correspondto the frequency range covered by a set of interlaces.

Configuring a terminal or wireless device or node may compriseinstructing and/or causing the terminal or wireless device or node tochange its configuration, e.g. at least one setting and/or registerentry and/or operational mode. A terminal or wireless device or node maybe adapted to configure itself, e.g. according to information or data ina memory of the terminal or wireless device. Configuring a node orterminal or wireless device by another device or node or a network mayrefer to and/or comprise transmitting information and/or data and/orinstructions to the wireless device or node by the other device or nodeor the network, e.g. allocation data or configuration data and/orscheduling data and/or scheduling grants. Configuring a terminal mayinclude sending allocation data to the terminal indication whichmodulation and/or encoding to use. A terminal may be configured withand/or for scheduling data and/or to use, e.g. for transmission,scheduled and/or allocated uplink resources, and/or, e.g. for reception,scheduled and/or allocated downlink resources. Uplink resources and/ordownlink resources may be scheduled and/or provided with allocation orconfiguration data.

A first cell may generally be a cell of a licensed cellular network,e.g. LTE. It may be a PCell and/or a cell intended to carry control andcommand information, in particular for the PCell and/or the second cell,for example a LA SCell.

A second cell and/or second uplink carrier, respectively second downlinkcarrier, generally may be a cell and/or uplink carrier, respectivelydownlink carrier, of a non-licensed network and/or a cell and/or uplinkcarrier, respectively downlink carrier, on which a LBT procedure has tobe performed/has been performed before transmission of data, inparticular a LA SCell. Control information/scheduling for the secondcell may be transmitted on the first cell, e.g. to providelicensed-assisted controlling and scheduling.

An uplink carrier may generally be or indicate a carrier and/orfrequency band intended and/or used for uplink transmissions.

A downlink carrier may generally be or indicate a carrier and/orfrequency band intended and/or used for downlink transmissions.

A carrier may generally be an unlicensed carrier and/or be accessed fortransmission based on and/or after a successful LBT procedure. A channelmay generally be a physical channel and/or defined by comprising and/orbeing associated to one or more (radio and/or time/frequency) resources,in particular resource elements or resource blocks.

Interlacing may generally comprise transmitting on resources such thatthe transmitting device transmits on frequencies or frequency resourcesthat are separated by one or more frequency units (e.g., smallestfrequency unit, or in particular a frequency range covered by a resourceblock). The separating units may be frequency units on which thewireless transmitter does not transmit (with the exception of undesiredleakage or interference, which may appear due to physical reasons).Generally, interlacing may in particular pertain to interlaces definedin regard to resource blocks (respectively, the corresponding frequencyrange covered by a RB). Interlacing may comprise transmitting one ormore interlaces and/or on one or more interlaces.

Generally, interlacing may comprise mapping and/or scheduling one ormore interlaces on resources, which may be scheduled resources.Scheduled resources may be scheduled and/or configured by the wirelesstransmitter, for example for downlink or uplink transmission. Scheduledresources may pertain to one or more resource units, in particularresource blocks and/or cover a plurality of frequency units, e.g. acarrier (which comprises a plurality of subcarriers). For uplinktransmission, scheduled resources may be configured by another wirelesstransmitter, e.g. a network node. Mapping may generally be performed bya wireless transmitter itself, e.g. based on scheduled resources (e.g.,a network node or terminal may perform the mapping itself, e.g. via amapping module). Alternatively, the mapping may be performed by aconfiguring transmitter, e.g. a network node (in this case, the mappingmay be indicated via allocation and/or configuration data, and/orinterlacing may comprise transmitting according to scheduled resourcesand/or based on the indicated mapping).

An interlace may be defined regarding a frequency structure and/orassociated resource structure such that an interlace comprises and/orcovers a plurality of frequency units (and/or associated resourceunits), e.g., a number of Nu units, one of which is and/or may be usedfor transmission, wherein one or more others (e.g., Nu-1) are not usedfor transmission. The units in particular may be resource blocks. Nu mayin on example be 6 or a multitude of 6.

The frequency units of an interlace may be continuous and/or contiguousin frequency. It may be considered that an interlace is generallydefined pertaining to widths in frequency, rather than a specificfrequency range (notwithstanding the possibility that differentinterlace may be defined for different frequency ranges, e.g. due todifferent protected intervals defined by regulations, and/or that aspecific interlace would be defined and/or map the interlace structureto a specific frequency range). In particular, an interlace may cover acontinuous or contiguous frequency range, which may be referred to asinterlace range.

The frequency unit of an interlace used for transmission may be referredto as transmission unit, the other units may be referred to asnon-transmission unit. A unit of an interlace may in particular be aresource block, respectively a frequency unit may correspond to theassociated frequency range of a resource block. Generally, interlacingmay comprise transmitting one or more interlaces (e.g., continuousand/or contiguous interlaces), which may thus include transmitting on anumber of transmission units corresponding to the number of interlaces.

It may be considered that for interlacing, the transmission unit is atone of the borders of the frequency range covered by the interlace, e.g.at the highest or lowest frequencies of the interlace. The samearrangement of transmission unit in the interlace may be used fordifferent interlaces (covering different frequency ranges) forperforming interlacing. It may be considered that transmission units ofinterlaces are arranged such that each protected interval (e.g., of asystem bandwidth) includes at most one transmission unit (transmissionresource block).

An interlace or set of interlaces, respectively corresponding resources,may be considered to represent a cluster of resources, due totransmission units (a frequency or resource unit used or scheduled fortransmission) and/or resources used or scheduled for transmission beingclustered between transmission units and/or resources not used orscheduled for transmission. In this context, arranging a singletransmission unit or resource, or more than one transmission unit orresource, between (regarding neighboring frequencies or frequency unitslike subcarriers) frequency or resource units not scheduled fortransmission may be seen as clustering. Generally, clustering maypertain to, at least partly over a frequency range, in particular therange covered by one or more resource blocks, arranging transmissionunits (in particular, subcarriers) non-contiguous to other transmissionunits (at least on one side).

Scheduled resources and/or a resource allocation may indicate and/orcomprise an interlace pattern. The resources or allocation may betransmission resources, in particular uplink transmission resources,and/or may be associated or allocated to a specific device, e.g. awireless transmitter like a terminal (which may have been allocated theresources by a network node like an eNodeB, or a network node, which mayhave allocated the resources to itself). The pattern may comprise one ormore sets of interlaces. One or more, in particular each, set/s, and/orthe pattern, may be periodic and/or quasi-periodic, in particular interms of location and/or arrangement of transmission units (inparticular, subcarriers) or resources in frequency. It may be consideredthat the set/s and/or pattern is block-wise periodic or quasi-periodic.Block-wise (quasi-) periodicity may refer to a specific pattern oftransmission units (in particular, subcarriers) being repeated (infrequency domain) over a frequency range for a plurality of times (twiceor more, in particular 5 times or more). The (quasi-)periodicity may beconsidered block-wise, if the repeated pattern covers only a part of theinterlace pattern of the scheduled resources or resource allocation.

An interlace pattern may comprise a plurality of repeating patterns, inparticular of block-wise repeating patterns. The individual repeatingpatterns may be different. The repeating pattern/s may be associatedand/or be dependent on interlaces and/or sets of interlaces theinterlace pattern comprises. The interlace pattern may generally bedefined and/or configured based on interlace indications or interlaceset indications (which may be represented by configuration data orallocation data). A repeated pattern may be considered quasi-periodic ifone or more transmission units (in particular, subcarriers) are slightlyshifted away from periodicity in the frequency domain. A slight shiftmay be a shift of one or two width of a transmission unit widths (inparticular, subcarrier widths) up or down, and/or a shift for a distance(in frequency domain) lower than 10% or lower than 5% of the totalfrequency range covered by the repeated pattern. A periodic orquasi-periodic repeated pattern may have transmission units or clustersof neighboring or contiguously arranged transmission units (inparticular, subcarriers or blocks or clusters of subcarriers)equidistantly arranged (in regard to frequency domain). The distance infrequency domain may for example be in frequency or frequency units, inparticular in subcarriers (and/or smallest frequency units).

Interlacing may generally comprise performing a DFT-OFDM modulation forsignals to be transmitted, in particular based on scheduled resources ora resource allocation, which may comprise or indicate an interlacepattern. Performing modulation may comprise and/or be based on aRB-to-subcarrier mapping, e.g. of QAM-modulated signals. DFT-OFDMmodulated signals on scheduled resources or a resource allocation. Themodulation may be a clustered modulation and/or a DFT-S-OFDM(DFT-spread-OFDM) modulation. The modulation may be performed asdescribed herein. A wireless transmitter may be adapted for performingsuch modulation and/or comprise a modulation module for such modulation.A DFT-OFDM modulation may be considered clustered, as and/or when it isperformed on clustered resources, e.g. an interlace pattern as describedherein.

An interlace pattern may generally comprise and/or indicate one or moresets of interlaces. The pattern may indicate or comprise frequency units(e.g., subcarriers) and/or resources available and/or scheduled fortransmission, e.g. resource blocks and/or one or more transmissionunits, e.g. subcarriers. The pattern may be indicated by configurationdata and/or allocation data.

A wireless transmitter, in particular a network node, may configure,and/or be adapted for configuring and/or comprise a configuring modulefor configuring, one or more wireless transmitters, e.g. terminals, forperforming interlacing, and/or for utilizing a set of interlaces fortransmitting, e.g. by allocating or configuring the resourcescorresponding to a set of interlaces to a terminal, for example bytransmitting corresponding configuration or allocation data.

Performing interlacing and/or transmitting based on a frequencystructure and/or resource structure may refer to following and/orutilizing the structure when transmitting.

Interlacing, and/or transmitting in particular in the context ofinterlacing, may comprise performing an LBT procedure, and/or may bedependent on a successful LBT procedure, e.g. for the transmission unitand/or the interlace including the transmission unit. Interlacing,and/or transmitting in particular in the context of interlacing, maycomprise transmitting such that in the/each transmittingunit/transmitting resource block of an interlace the maximum allowablepower or PSD and/or a power up to the maximum allowable power or PSD fora protected interval is used for transmission. It may be considered thatinterlacing or transmitting comprises transmitting such that in averageover a pre-determined number of time units (e.g., slots and/or subframesand/or time units associated to a resource structure or resource unit)in the transmitting unit/transmitting resource block of an interlace themaximum allowable power or PSD and/or a power up to the maximumallowable power or PSD for a protected interval is used fortransmission. This maximum power/PSD may be defined as requirement orcondition for the protected interval in which the transmitting unit isarranged and/or covered by the interlace.

A Sounding Reference Signal may generally be a reference signal, whichmay be provided, e.g., to estimate channel status and/or channel qualityand/or timing/synchronization. A receiver of such a reference signal maygenerally know the power of transmission and/or an expected timing ofthe reference signal, and be adapted to compare this power oftransmission with the received power for such estimation.

It may be considered that the reference signal, in particular a SRS, isan uplink signal, which may be intended for a network node like aneNodeB, and/or a sidelink signal, which may be intended for anotherterminal. The network and/or network node may be adapted to configure aterminal transmitting reference signals/SRS with the power oftransmission and/or the power of transmission may be defined by astandard. There may be different kinds of reference signals/SRS, e.g.cell-specific signals or terminal/UE-specific signals. A terminal may beconfigurable for reference signal/SRS transmission, and/or a networknode like an eNodeB may be adapted for such configuring and/or performsuch configuring. Configuring for reference signal transmission maycomprise configuring timing, e.g. where in a time-structure like asubframe or slot the SRS is to be transmitted, and/or frequency oftransmission (how often/in which time-intervals transmission is to beperformed) and/or resource/s used for transmission, which resourceelement/s.

A resource element may be considered to be a form of time/frequencyresource, in particular the smallest unit defined for such resource. Aresource element may in particular comprise one subcarrier (in frequencydomain) and one symbol (in time domain).

Some useful abbreviations include:

Abbreviation Explanation SRS Sounding reference signal DMRS Demodulationreference signals eNB Evolved NodeB, base station UE User Equipment ULUplink LAA Licensed-Assisted Access RS Reference Signal SCell SecondaryCell LBT Listen-before-talk LTE-U LTE in Unlicensed Spectrum PUSCHPhysical Uplink Shared Channel PUCCH Physical Uplink Control Channel CACarrier Aggregation CoMP Coordinated Multiple Point Transmission andReception CQI Channel Quality Information CRS Cell-specific ReferenceSignal CIS Channel State Information CIS-RS CIS reference signal D2DDevice-to-device DL Downlink EPDCCH Enhanced Physical DL Control CHannelDL Downlink; generally referring to transmission of data to a node/in adirection further away from network core (physically and/or logically);in particular from a base station or eNodeB to a D2D enabled node or UE;often uses specified spectrum/bandwidth different from UL (e.g., LTE)eNB evolved NodeB; a form of base station, also called eNodeB E-UTRA/NEvolved UMTS Terrestrial Radio Access/Network, an example of a RAT FDDFrequency Division Duplexing ID Identity L1 Layer 1 L2 Layer 2 LTE LongTerm Evolution, a telecommunications standard MAC Medium Access ControlMBSFN Multiple Broadcast Single Frequency Network MDT Minimization ofDrive Test NW Network OFDM Orthogonal Frequency Division MultiplexingO&M Operational and Maintenance OSS Operational Support Systems PC PowerControl PDCCH Physical DL Control CHannel PH Power Headroom PHR PowerHeadroom Report PSS Primary Synchronization Signal PUSCH Physical UplinkShared CHannel R1, R2, . . . , Rn Resources, in particulartime-frequency resources, in particular assigned to correspondingcarrier f1, f2, . . . , fn RA Random Access RACH Random Access CHannelRAT Radio Access Technology RE Resource Element RB Resource Block RRHRemote radio head RRM Radio Resource Management RRU Remote radio unitRSRQ Reference signal received quality RSRP Reference signal receivedpower RSSI Received signal strength indicator RX reception/receiver,reception-related SA Scheduling Assignment SL Sidelink, pertains to D2Dtransmission (Device-to- Device), between terminals, which may besupported by or independent of the network; a SL may use ULcarrier/bandwidth (in particular FDD) SINR/SNRSignal-to-Noise-and-Interference Ratio; Signal-to- Noise Ratio SFNSingle Frequency Network SON Self Organizing Network SSS SecondarySynchronization Signal TPC Transmit Power Control TXtransmission/transmitter, transmission-related TDD Time DivisionDuplexing UE User Equipment UL Uplink; generally referring totransmission of data to a node/in a direction closer to a network core(physically and/or logically); in particular from a D2D enabled node orUE to a base station or eNodeB; in the context of D2D, it may refer tothe spectrum/bandwidth utilized for transmitting in D2D, which may bethe same used for UL communication to a eNB in cellular communication;in some D2D variants, transmission by all devices involved in D2Dcommunication may in some variants generally be in UL spectrum/bandwidth/carrier/frequency

These abbreviations may be interpreted according to the LTE or a relatedstandard.

What is claimed is:
 1. A User Equipment for a MulteFire wirelesscommunication network, the User Equipment comprising processingcircuitry and a transmitter, the User Equipment being adapted forutilizing the processing circuitry and the transmitter for: performing aListen-Before-Talk (LBT) procedure for one or more transmissionbandwidths; transmitting Physical Uplink Shared CHannel (PUSCH)signaling in a PUSCH subframe on one or more interlaces within the oneor more transmission bandwidths; and transmitting Sounding ReferenceSignaling on the one or more interlaces in the PUSCH subframe.
 2. TheUser Equipment of claim 1, wherein transmitting Sounding ReferenceSignaling comprises transmitting Sounding Reference Signaling at the endof the PUSCH subframe, in particular in the last symbol of the PUSCHsubframe.
 3. The User Equipment of claim 1, wherein transmittingSounding Reference Signaling comprises multiplexing Sounding ReferenceSignaling transmitted on different antenna ports via frequency divisionand/or based on cyclic shifts.
 4. The User Equipment of claim 3, whereintransmitting Sounding Reference Signaling comprises transmittingSounding Reference Signaling at the end of the PUSCH subframe, inparticular in the last symbol of the PUSCH subframe.
 5. A method foroperating a User Equipment in a MulteFire wireless communicationnetwork, the method comprising: performing a Listen-Before-Talk (LBT)procedure for one or more transmission bandwidths; transmitting PhysicalUplink Shared CHannel (PUSCH) signaling in a PUSCH subframe on one ormore interlaces within the one or more transmission bandwidths; andtransmitting Sounding Reference Signaling on the one or more interlacesin the PUSCH subframe.
 6. The method of claim 5, wherein transmittingSounding Reference Signaling comprises transmitting Sounding ReferenceSignaling at the end of the PUSCH subframe, in particular in the lastsymbol of the PUSCH subframe.
 7. The method of claim 5, whereintransmitting Sounding Reference Signaling comprises multiplexingSounding Reference Signaling transmitted on different antenna ports viafrequency division and/or based on cyclic shifts.
 8. The method of claim7, wherein transmitting Sounding Reference Signaling comprisestransmitting Sounding Reference Signaling at the end of the PUSCHsubframe, in particular in the last symbol of the PUSCH subframe.
 9. AnAccess Point for a MulteFire wireless communication network, the AccessPoint comprising processing circuitry and a receiver, the Access Pointbeing adapted for utilizing the processing circuitry and the receiverfor: estimating channel conditions based on Sounding Reference Signalingreceived from at least one User Equipment for the MulteFire wirelesscommunication network; wherein receiving Sounding Reference Signalingcomprises receiving Physical Uplink Shared CHannel, PUSCH, signaling ina PUSCH subframe on one or more interlaces, and receiving SoundingReference Signaling on the one or more interlaces in the PUSCH subframe.10. The Access Point of claim 9, wherein Sounding Reference Signaling istransmitted at the end of the PUSCH subframe, in particular in the lastsymbol of the PUSCH subframe.
 11. The Access Point of claim 9, whereinSounding Reference Signaling transmitted on different antenna portsand/or by different terminals is multiplexed via frequency divisionand/or based on cyclic shifts.
 12. The Access Point of claim 11, whereinSounding Reference Signaling is transmitted at the end of the PUSCHsubframe, in particular in the last symbol of the PUSCH subframe.
 13. Amethod for operating an Access Point in a MulteFire wirelesscommunication network, the method comprising: estimating channelconditions based on Sounding Reference Signaling received from at leastone User Equipment for the MulteFire wireless communication network;wherein receiving Sounding Reference Signaling comprises receivingPhysical Uplink Shared CHannel, PUSCH, signaling in a PUSCH subframe onone or more interlaces, and receiving Sounding Reference Signaling onthe one or more interlaces in the PUSCH subframe.
 14. The method ofclaim 13, wherein Sounding Reference Signaling is transmitted at the endof the PUSCH subframe, in particular in the last symbol of the PUSCHsubframe.
 15. The method of claim 13, wherein Sounding ReferenceSignaling transmitted on different antenna ports and/or by differentterminals is multiplexed via frequency division and/or based on cyclicshifts.
 16. The method of claim 15, wherein Sounding Reference Signalingis transmitted at the end of the PUSCH subframe, in particular in thelast symbol of the PUSCH subframe.